Bubo sp.

Pavia, Marco, Manegold, Albrecht & Haarhoff, Pippa, 2015, New early Pliocene owls from Langebaanweg, South Africa, with first evidence of Athene south of the Sahara and a new species of Tyto, Acta Palaeontologica Polonica 60 (4), pp. 815-828 : 823-824

Bubo sp.

Fig. 3C .

Material. —Left tibiotarsus, SAM-PQ-L28439C, distal end from Langeberg Quartz Sand Member or Muishond Fontein

Pelletal Phosphorite Member of the Upper Varswater Formation at Langebaanweg, early Pliocene of South Africa.

Measurements. —Distal width 13.3 mm; distal depth> 10.5mm see Table 9).

Remarks. —The distal tibiotarsus can be referred to Strigidae rather than to Tytonidae because of the following morphological characteristics: (i) two condyli parallel and wide in distal view; (ii) condylus medialis not tilted medially; (iii) depression on the distal part of the shaft just above the trochlea cartilaginis tibialis deep in caudal view; (iv) epicondylus lateralis well developed. The specimen is comparable in size to the extinct B. leakeyae from the Early Pleistocene of Olduvai Brodkorb and Mourer-Chauviré 1984), thus bigger than the Recent B. africanus and smaller than B. lacteus ( Table 9). According to Brodkorb and Mourer-Chauviré (1984: 22), B. leakeyae and B. africanus are distinguished from B. bubo by a more developed and more medially situated tuberositas retinaculi medialis, but, unfortunately, this character is not discernible in the Langebaanweg specimen. The fossil here described is also not comparable to Bubo cf. lacteus from the Pliocene of Laetoli and the Pleistocene of Olduvai ( Brodkorb and Mourer-Chauviré 1984; Louchart 2011) as no distal tibiotarsi are known for these taxa from the aforementioned localities. The fossil tibiotarsus from Langebaanweg is thus referable to a medium-sized species of the genus Bubo , apparently smaller than the largest extant species of eagle owls in Africa, i.e., B. lacteus , B. shelleyi , and B. (Scotopelia) peli . Because the specimen is only poorly preserved, we abstain from referring it to any particular species of this genus.

Figures

Fig. 3. Strigid owls from the early Pliocene, Upper Varswater Formation at Langebaanweg, South Africa. A. Asio sp. (SAM-PQ-L33521 I), right tibiotarsus, in cranial (A 1), lateral (A 2), caudal (A 3), medial (A 4), and distal (A 5) views. B. Strigidae gen. et sp. indet. (SAM-PQ-L28479 C), left tibiotarsus in cranial view. C. Bubo sp. (SAM-PQ-L28439 C), left tibiotarsus in cranial view.